Can I tell by smell or taste if my water is contaminated?

Not necessarily. You might be able to notice a few unappetizing things that could wind up in your drinking glass – like the distinctive rotten-egg smell of hydrogen sulfide or a strong taste from too much chlorine (a necessary additive to kill harmful microorganisms). But some of the most serious and common contaminants, including bacteria, viruses, arsenic, lead, industrial and agricultural pollutants, have no flavor or odor.

So how can I tell whether my water is safe to drink?

It depends on whether your water comes from a public (municipal) water system or a private well. (Unless you live in a rural area and have a private or shared well, your water probably comes from a municipal system.)

Every water system that supplies at least 25 people is required to comply with the federal Safe Drinking Water Act (SDWA), which mandates that the supplier test its water regularly and provide you with an annual copy of the results, called a Consumer Confidence Report (CCR). You can also get a copy of this report any time by calling the phone number on your water bill. The supplier must also issue a public alert if any potentially harmful contaminants are found to be above acceptable limits.

Or you can check the safety history of your water system through the Safe Drinking Water Information System (SDWIS) database maintained by the United States Environmental Protection Agency (EPA). Click on your state and county, then choose your water system from the list. These results show if there have been any recent reports of contaminants in your water system.

However, federal drinking water standards don't apply to private wells, so it's your responsibility to check the quality of your water if you have a well.

How can I test my water if I have a well?

Since federal drinking water standards don't apply to private wells, it's up to you to have your water tested (and to pay for the test). Check the EPA's listing of certified labs for testing drinking water.

Your local health department or state extension service can advise you about which tests are the most important ones to do in your area.

For example, if you live in an agricultural area, you may want to test your water for pesticides commonly used there. And if you live where gas or oil well drilling is done, you may want to test for such chemicals as bromide, barium, methane, ethane, or total petroleum hydrocarbons.

Wherever you live, have your well water tested at least once a year for nitrates, coliform bacteria (bacteria found in the intestines), pH, and "total dissolved solids." These are inorganic salts (like sodium, chloride, and sulfate) and small amounts of organic matter. This test is especially important if your well is new, or if you've recently repaired or replaced pipes.

This annual test gives you one measurement of the total solids dissolved in your water, but it doesn't tell you which ones they are or the amount of each one.

That's why it's also a good idea to test your water every three years for chloride, iron, sulfate, and manganese. Depending on where you live, you may also need annual checks for lead, copper, arsenic, radon, pesticides, or other substances.

If your test results indicate a problem, you'll need to determine how to correct it. This might mean having the well evaluated to see if there's a problem with the construction. Or it might mean that the water needs to be treated by disinfection, shock chlorination, or a process called reverse osmosis.

To learn more about well water testing, including when you might want to test more often than annually, how to interpret test results, and how to address problems, visit The National Ground Water Association (NGWA) website.

Should I test my municipal tap water at the faucet?

It's not a bad idea, especially if you have specific concerns, like lead or nitrate contamination. (Nitrate is a chemical found in sewage, animal manure, and synthetic fertilizer.) It is possible for water to become contaminated between the treatment plant and your drinking glass.

Contact your local water agency and ask if they'll do a test. You can also ask your county health department, which may provide testing for certain contaminants, such as lead and nitrate. (There's usually a fee for the service.)

If your water supplier or county health department won't test your water at the faucet, you can have the test done by a state-certified lab. Check the EPA's list of certified labs for testing drinking water to find one in your area.

The lab will most likely have recommendations about which tests to do, and these will vary depending on where you live and whether you have a specific concern (like if your water has a particular smell or taste).

You'll also be instructed how to collect the sample, and in some cases (if you're testing for bacterial contaminants, for example), you may be given sterilized containers to use. You may have to collect "first-draw water," or the water that comes out of your faucet when you first turn on the tap in the morning. For other tests, you may have to let the water run for a certain amount of time before collecting a sample.

Choose a lab that's nearby because you may have to deliver the sample yourself. And depending on which tests you're doing, the water sample may need to be kept on ice and tested no later than 24 to 30 hours after it's drawn.

The cost of a water test can run from $30 to screen for one or two specific contaminants to $500 or more to screen for multiple ones. You can also use a home kit to test your water yourself. These kits can't test for everything (and they may not be as accurate as a lab test), but they can detect lead, arsenic, pesticides, and bacteria. Such kits sell for $10 to $165.

When should I test my tap water for nitrate?

If you have well water, you may want to test it for nitrate while you're pregnant, just after your baby is born, and sometime during the next six months. If you have municipal water service, you don't need to test nitrate levels yourself because these are reported in the CCR.

Exposure to high levels of nitrate during pregnancy has been linked to birth defects, such as spina bifida and cleft palate, and babies younger than 1 are especially vulnerable to nitrate poisoning.

Don't worry about this problem if you're breastfeeding exclusively because even water that's contaminated with nitrate won't affect your baby through breast milk.

But exposure to high levels of nitrate from water that's mixed with powdered baby formula or given directly to a baby can cause methemoglobinemia, a blood disorder also known as "blue baby" syndrome. This condition affects the hemoglobin in a baby's blood, causing the oxygen supply to drop dangerously low.

When should I test for lead and copper in my tap water?

Have your water tested for lead if you have lead pipes or brass faucets (which may contain lead) and for copper if you have copper pipes. Copper pipes are brown, like an old penny.

It can be a little trickier to determine if your pipes are lead, but you should still be able to tell without the help of a plumber. Lead pipe is gray and is only likely to be found in homes built before the 1980s.

However, some old homes may have galvanized steel pipes, which are also gray. One way to tell the difference is to check how the pipes are connected: Galvanized steel pipes are magnetic and threaded at the joints. Lead pipes are not magnetic, so the ends are bulblike and fit over the receiving pipe.

Water contaminants are measured by how many particles of the substance are present in a billion particles of water, and lead can be very dangerous to children in concentrations of more than 15 parts per billion (ppb). All lead pipes should be replaced.

Copper isn't nearly as toxic as lead, but it can still be harmful in high concentrations. This is usually only a problem if the water is acidic. In that case, some copper from the pipe might dissolve and leach into the water as it sits in the pipe.

Testing your water annually is the only way to determine if you definitely have a problem with copper contamination. Depending on the level of copper in your water and the pH, you might need a neutralizing system to makes the water less acidic, or you might need to replace the copper pipes.

Are we better off drinking bottled water?

Not necessarily. Although the Food and Drug Administration (FDA) sets maximum allowable limits for many harmful substances, bottled water manufacturers aren't required to make their products completely free of contaminants. The quality of bottled water can vary, depending on where it originated (whether it's spring water, municipal water, or well water) and how it was treated.

In addition, the FDA doesn't require bottlers to include naturally occurring compounds (such as sodium or sulfates) on their lists of ingredients, though these compounds also must be below the maximum levels set by FDA regulations.

If you're concerned, ask the bottled water company for a detailed independent analysis of their water.

Some bottled water is certified by NSF International, an independent, third-party nonprofit that monitors the quality of bottled water. NSF's consumer website has useful information about the different types of bottled water available and where the water comes from. Look for the NSF mark on the bottled water you buy to ensure that it's been carefully tested.

Should I use a water filter?

It depends on what contaminants you're trying to remove. Before you purchase a water treatment unit, have your water tested so that you know exactly which contaminants are in your water and which type of filtration system will best suit your needs – options range from a simple countertop model or system that filters all the water that enters your house. Then search the NSF International database of certified drinking water treatment units to find out which ones will remove those contaminants.

It's also important to be aware that two types of home filtration systems (reverse osmosis and distillation systems) can remove fluoride from the water. Fluoride is added to municipal water systems to build tooth enamel and prevent decay. If you're using one of these systems, talk to your dentist or doctor about how to make sure your child gets adequate fluoride from other sources.

If you purchase a countertop water filter, follow the manufacturer's instructions for use and change the filter regularly to prevent contaminants from building up.

Note: This article was reviewed by Craig Mains, engineering scientist at the National Environmental Services Center at West Virginia University in Morgantown.

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